In recent years, in view of an increase in energy-saving consciousness and anxiety about electric power supply, enterprises and public facilities take power saving measures by means of collecting natural light as far as possible, culling out illuminations, or the like. However, there was a concern that comfort or safety is impaired because of a shortage of illuminance due to this power saving. In addition, from the viewpoint of power saving, although LED illuminations which are low in power consumption and long in life are watched, there was involved such a problem that a difference in light and darkness is easily generated even in the same room depending upon a place because of high directivity.
As for these problems, there is made an attempt such that a reflecting plate is disposed in an inner wall, a ceiling, or the like to effectively reflect natural light or illumination light and diffuse the indirect light every nook and corner of the space of the room, thereby increasing the illuminance. In such a reflecting plate, in order to suppress a lowering of the light quantity when the light is reflected on the reflecting plate, a surface of the reflecting plate is required to have high reflecting properties to visible light. Specifically, for example, it is proposed to use a coated steel sheet having a high degree of whiteness. However, in the case of using a coated steel sheet having a high gloss value, although a place irradiated with light causes specular reflection, so that partial brightness is felt, it was difficult to make the surroundings irradiated with light evenly bright.
As for the above-described problem, as conventional light diffusion reflecting materials, for example, those described in PTL 1 are exemplified. PTL 1 proposes a light diffusion reflecting material comprising a covering layer composed of plural layers of two or more layers on a surface of a base material, wherein a non-metallic sheet-like filler is contained in a light diffusion layer of the outermost layer of the plural layers, and rutile type titanium oxide is contained in a visible light reflecting layer which is the thickest among the layers sandwiched between the light diffusion layer and the base material.